
I've been using consecutive builds of the beta successfully on 2 machines now, and I truly believe 7 is going to be what Vista was supposed to. The slew of new features and GUI tweaks I started using make it a bit inconvenient when I return to my production OS.
Also today, Microsoft announced a new feature that will allow people (and developers) who are still attached to XP to migrate easily. It was formerly known as Virtual XP (VXP), but Microsoft renamed it XPM - XP Mode.
Essentially, this is a virtual window running Windows XP, inside Windows 7 - without the need to install VPC or VMWare. The virtualization functionality is part of the OS. The feature will be released as an add-on to the system, and will be free for the business,
It remains to be seen if other operating systems could be installed in XPM. Oh, who am I kidding - 5 seconds after it's out, someone will hack it to run Mac OS X

And while on the subject of virtualization: last week Microsoft officially released MED-V, their desktop virtualization solution (based on a product by Kidaro, an Israeli start-up they acquired). While I recommend reading more about it, essentially it allows running separate applications in a virtual environment (not a full machine). This allows for compatibility and manageability of applications in enterprise environment.
Example: if you're using IE8, but all your corporate software can only run on IE6 (and the two browsers cannot be installed side-by-side), you could install IE6 into a virtual MED-V environment (perhaps running an older OS) and have the 2 browsers up and running at the same time.
With all those virtualization features integrated into the current and next generations of the operating system, I have to wonder what does VMWare plan to do? Perhaps concentrate on Linux or Mac OS? Will virtualization become OEM technology like VNC and web remoting? Interesting times ahead...